Recent developments in the automotive industry have focused upon elimination of wiring harnesses and wiring boxes beneath vehicle instrument panels. One development, which is described in U.S. patent application Ser. No. 08/642,723, which is assigned to the assignee of the present application, discloses a method of overlaying circuit patterns directly onto instrument panel structural components. This method is very promising in that it reduces vehicle weight, reduces assembly and packaging problems, and simplifies the overall design.
A problem experienced with the application of circuit patterns directly onto vehicle structural components is that such structural components are typically three-dimensional or non-planar, therefore the circuit pattern must be applied onto the non-planar surface. Accordingly, dispensing solder paste onto discrete locations on the circuit pattern to form electrically conductive solder joints once the circuit pattern has been applied to the non-planar surface is problematic because efficient technology does not exist for applying solder at a plurality of discrete locations on a non-planar surface.
Screen printing approaches require substantially flat surfaces and require special tooling and construction features of limited utility for printing in recesses. Syringe dispensing is possible with many three-dimensional surfaces, however, x-direction and y-direction dispense head travel speed along with z-axial and theta angle positioning require a prohibitively long time in a high speed manufacturing scenario.
The same problem exists in applying surface-mounted electronic devices to non-planar surfaces. These surface-mounted electronic devices typically require an adhesive to hold the device in place when applied to an angled surface. However, efficient technology does not exist for rapidly applying such adhesive at discrete locations on non-planar surfaces.
Accordingly, it is desirable to provide a method and apparatus for applying solder paste and other fluids, such as glue, to non-planar three-dimensional substrates.